Studies of human lung pathology were continued in order to identify the conditions under which silicotic lung lesions are accompanied by alveolar type II epithelial hyperplasia and adenomatoid lesions, adjacent to areas of fibrosis, and their association with lung adenocarcinomas. Histological material was examined from a pilot study, designed in collaboration with NIOSH and with the Epidemiology Program, NCI, in order to characterize epithelial proliferative lesions and lung cancers by histologic type in a sample from a large population of uranium miners from the Saxony region in Germany, that received heavy exposures to silica and/or radiation especially in the 1950s and '60s. This population includes over 15,000 cases of silicosis and 5,000 cases of lung cancer, for which exposure histories and autopsy records are available for over 90% of cases. The histological lesions in the pilot study were examined and classified blindly by several pathologists. Further studies have continued to characterize the lesions induced by crystalline silica in the rat model for silicosis-associated lung carcinogenesis.